1. Field of the Invention
This invention relates generally to a guideway and levitation system for transport vehicles, and more particularly concerns a system for maglev track/guideway emplacement on existing rail lines that can be used by both maglev vehicles and conventional trains. The emplacement is compatible with, and can be used by, maglev vehicles that can also travel on high speed dedicated guideways.
2. Description of Related Art
Interest in passenger and freight ground vehicles levitated by magnetic forces has grown with new advances in materials and technology, and as needs have increased for transportation systems that can minimize environmental and noise pollution, that are more energy efficient, and that can reduce the traffic congestion and improve travel safety. Magnetic levitation transportation systems have been proven in pilot projects to be able to achieve speeds of 300 miles per hour and faster.
Vehicles that are levitated magnetically without contacting a support surface encounter reduced friction and vibration problems due to roadbed irregularities. An early system provided for a train levitation system based on the magnetic repulsion generated between two superconducting loops carrying D.C. current, one on a moving train and one on a stationary track. In a subsequent system, the superconducting magnets interacted with a plurality of arrays of longitudinally extending shorted loops of a non-magnetic metal conductor, such as aluminum, in a guideway. The vehicle was suspended over the guideway by magnetic interaction of the superconducting magnets with the shorted loops in the guideway. The vehicle was supported on wheels when at rest, or when it was started, or operated at transitional speeds below that necessary to suspend the vehicle. Vertical lift was provided by magnetic interaction of the superconducting magnets with coils in the form of individual shorted loops. Horizontal stability was provided by magnetic interaction of the superconducting magnets with coils arranged in a FIG. 8 shape or in the form of a longitudinally extending series of two vertically spaced, electrically separated loops. The superconducting magnets were accommodated in a coolant container of a car of the train, and auxiliary and emergency support devices, such as wheels and a fixed skid, were provided support in the event that the levitation of the train was terminated in use, such as if the superconducting magnets became normal. The train was propelled by a linear synchronous motor, in which thrust was obtained by providing AC current to propulsion windings on the ground, which magnetically interacted with, and pushed forward the superconducting magnets located on the car of the train.
Previous studies of maglev guideways have typically focused on designing and building dedicated structures that can only carry maglev vehicles, whether for passengers or freight. These guideways are usually elevated structures that can be constructed in the field, or prefabricated and assembled from factory produced components such as beams and piers, with poured footings.
On many sections of railroad track in the United States, train speed is considerably less now than it was decades ago, due to deterioration of the road bed. The current costs of building new access ground transport routes to urban areas is extremely high, typically hundreds of millions of dollars per mile, and is normally much greater than building new routes in rural areas. In addition, the time required for obtaining new access areas for transportation routes in urban areas can be a very long, and expensive process.
In order to reduce costs of implementation and reduce the need for obtaining additional rights of way for high speed transportation routes, it would be desirable to provide a maglev guideway emplacement on existing rail lines that can be used by both maglev vehicles and conventional trains. This would enable maglev vehicles to travel at very high speed on dedicated guideways in low cost locations, i.e. rural and low population suburban areas, and transfer to existing railroad routes in high cost urban and high population suburban areas. Even with lower speed operation on such sections applied on existing rails, the average speed of maglev vehicles can be expected to remain almost as great as for a maglev route using only dedicated guideways. It would also be desirable to improve transportation capacity, and the ability to operate with closer headways, the distances in time or space that separate two vehicles or sets of vehicles traveling the same route.
It would also be desirable to provide a transportation that can be installed relatively quickly, without interfering with ongoing railroad operations, in virtually all of the United States, and particularly in population centers. It would also be desirable to provide a maglev track/rail transportation system that produces lower pressures on the ties and the ballast than is typically encountered with conventional trains. to reduce damage and degradation of the track and to minimize alteration of the position of the guideway emplacement. The present invention meets these needs.